High ranking chimps act as mediators

Conflict management is highly significant
for life in social groups, the researchers concluded in their findings
published in the magazine PLoS ONE. The study was based on the behaviour of a
group of hominids in the zoo at Gossau in Switzerland.

The team said it was astonishing that chimpanzees
were able to mediate in a conflict, without themselves deriving any immediate
advantage from their efforts.

“The rarest and most interesting form of
conflict management is policing, that is impartial interventions by bystanders,
which is of considerable interest due to its potentially moral nature,” they
said.

The team led by anthropologists Carel van
Schaik and Claudia Rudolf von Rohr observed a group of 11 chimpanzees (Pan
troglodytes), evaluating their natural behaviour without provoking conflict.
The group consisted of two adult and one young male, as well as six adult and
two young females.

Three of the adult females had joined the
group recently. Soon after the study began, three additional females were
introduced. At the same time there was conflict over ranking order among the
two adult males. These factors combined to cause instability in the group and
provided considerable grounds for disagreement.

Data collected between February 2007 and
November 2008 was then compared with that from studies conducted on chimpanzee
groups in zoos in Basel, Chester
in Britain and Arnheim in
the Netherlands.

The conflicts centred on competition among
the females for food and among the males for access to the females. The
researchers counted 438 conflict situations in their observation of the Gossau
group. Impartial mediators intervened in 69 cases.

In all cases, one of the two senior males
was the mediator.

Often merely approaching the squabbling
parties was sufficient, although in some cases making a clear threat or placing
himself between them was required. As many as 60 of these interventions proved
successful.

There were similar results from the Chester and Arnheim
studies, although senior females were also involved in mediation there.

The researchers noted that mediation was
not without its risks to the mediator, as he or she tended to draw the
aggression of the fighting parties. This could be the reason that animals high
up in the hierarchy were always involved.

There is a clear evolutionary advantage
from the mediation, as greater stability within the group furthers the survival
of all its members. “These results suggest that the primary function of
policing is to increase group stability. It may thus reflect pro-social
behaviour based upon community concern,” the team wrote.